janey68, nothing you have said really explains why MUMS attack each other. And why you just don't hear or see dads doing the same (or commenting much at all on parenting, in fact. It really would be worth you having a quick glance at Rebecca Asher's book - you don't have to read the whole thing, it is quite 'dip in and out-able' for specific areas.)
while I think an assumption that other parents are probably not idiots and probably do think about decisions affecting their children is v sensible, as is recognising that is is very rare to be completely in the picture about anyone's individual circumstances...
Your argument seems to be that parents shouldn't be making decisions based on what they think is best for their child. Or that they have some odd ideas about predicting outcomes that they shouldn't have.
That doesn't make sense. I do take into account, where I can, mainstream evidnce based info about what is best for my child. I chose to breastfeed - I know full well that it REDUCED the risk of some illnesses for my baby. I knew that did not mean it would GUARANTEE he would be illness free.
If there was a lot of decent evidence saying that babies were better off being looked after in fulltime childcare than by a parent, I'd be taking that into account. As it happens, there isn't - it tends to go the other way - so I am taking that into account. As damn inconvenient for my working life as it is! I know that encouraging my toddler to eat a healthy diet now won't GUARANTEE he is a healthy non obese adult. But it will give him a better chance than feeding him junk food. As a feminist and a mother, I want to be making responsible informed decisions wherever possible.
The argument that we can't possibly know how our children will ultimately turn out or be affected by our decisions doesn't mean that 'anything goes and therefore ALL choices are equally valid.' (it reminds me of my MIL's argument for not stopping smoking, which was that non smokers could get lung cancer too. Yeah - but they are a lot LESS likely to get it).
I do honestly think most parents understand they are dealing with possibilities and probabilities than guarantees.